S. Milker, A. Sydow, I. Torres‐Monroy, G. Jach, F. Faust, L. Kranz, L. Tkatschuk, D. Holtmann (2021) ,
Biotechnol. Bioeng. 118 (2021), 2694-2702. doi: 10.1002/bit.27788
Terpenoids have an impressive structural diversity and provide valuable substances for a variety of industrial applications. Among terpenes, the sesquiterpenes (C15) are the largest subclass with bioactivities ranging from aroma to health promotion. In this article, we show a gram-scale production of the sesquiterpene α-humulene in final aqueous concentrations of 2 g L−1 with the recombinant strain Cupriavidus necator pKR-hum in a fed-batch mode on fructose as carbon source and n-dodecane as an extracting organic phase for in situ product removal. Since C. necator is capable of both heterotrophic and autotrophic growth, we additionally modeled the theoretically possible yields of a heterotrophic versus an autotrophic process on CO2 in industrially relevant quantities. We compared the cost-effectiveness of both processes based on a production of 10 t α-humulene per year, with both processes performing equally with similar costs and gains. Furthermore, the expression and activity of 3-hydroxymethylglutaryl-CoA reductase (hmgR) from Myxococcus xanthus was identified as the main limitation of our constructed C. necator pKR-hum strain. Thus, we outlined possible solutions for further improvement of our production strain, for example, the replacement of the hmgR from M. xanthus by a plant-based variant to increase α-humulene production titers in the future.